Heading drift mitigation for low-cost inertial pedestrian navigation

The concept of autonomous pedestrian navigation is often adopted for indoor pedestrian navigation. For outdoors, a Global Positioning System (GPS) is often used for navigation by utilizing GPS signals for position computation but indoors, its signals are often unavailable. Therefore, autonomous pedestrian navigation for indoors can be realized with the use of independent sensors, such as low-cost inertial sensors, and these sensors are often known as Inertial Measurement Unit (IMU) where they do not rely on the reception of external information such as GPS signals. Using these sensors, a relative positioning concept from initialized position and attitude is used for navigation. The sensors sense the change in velocity and after integration, it is added to the previous position to obtain the current position. Such low-cost systems, however, are prone to errors that can result in a large position drift. This problem can be minimized by mounting the sensors on the pedestrian’s foot. During walking, the foot is briefly stationary while it is on the ground, sometimes called the zero-velocity period. If a non-zero velocity is then measured by the inertial sensors during this period, it is considered as an error and thus can be corrected. These repeated corrections to the inertial sensor’s velocity measurements can, therefore, be used to control the error growth and minimize the position drift. Nonetheless, it is still inadequate, mainly due to the remaining errors on the inertial sensor’s heading when the velocity corrections are used alone. Apart from the initialization issue, therefore, the heading drift problem still remains in such low-cost systems. In this research, two novel methods are developed and investigated to mitigate the heading drift problem when used with the velocity updates. The first method is termed Cardinal Heading Aided Inertial Navigation (CHAIN), where an algorithm is developed to use building ‘heading’ to aid the heading measurement in the Kalman Filter. The second method is termed the Rotated IMU (RIMU), where the foot-mounted inertial sensor is rotated about a single axis to increase the observability of the sensor’s heading. For the CHAIN, the method proposed has been investigated with real field trials using the low-cost Microstrain 3DM-GX3-25 inertial sensor. It shows a clear improvement in mitigating the heading drift error. It offers significant improvement in navigation accuracy for a long period, allowing autonomous pedestrian navigation for as long as 40 minutes with below 5 meters position error between start and end position. It does not require any extra heading sensors, such as a magnetometer or visual sensors such as a camera nor an extensive position or map database, and thus offers a cost-effective solution. Furthermore, its simplicity makes it feasible for it to be implemented in real-time, as very little computing capability is needed. For the RIMU, the method was tested with Nottingham Geospatial Institute (NGI) inertial data simulation software. Field trials were also undertaken using the same low-cost inertial sensor, mounted on a rotated platform prototype. This method improves the observability of the inertial sensor’s errors, resulting also in a decrease in the heading drift error at the expense of requiring extra components

Heading drift mitigation for low-cost inertial pedestrian navigation

The concept of autonomous pedestrian navigation is often adopted for indoor pedestrian navigation. For outdoors, a Global Positioning System (GPS) is often used for navigation by utilizing GPS signals for position computation but indoors, its signals are often unavailable. Therefore, autonomous pedestrian navigation for indoors can be realized with the use of independent sensors, such as low-cost inertial sensors, and these sensors are often known as Inertial Measurement Unit (IMU) where they do not rely on the reception of external information such as GPS signals. Using these sensors, a relative positioning concept from initialized position and attitude is used for navigation. The sensors sense the change in velocity and after integration, it is added to the previous position to obtain the current position. Such low-cost systems, however, are prone to errors that can result in a large position drift. This problem can be minimized by mounting the sensors on the pedestrian’s foot. During walking, the foot is briefly stationary while it is on the ground, sometimes called the zero-velocity period. If a non-zero velocity is then measured by the inertial sensors during this period, it is considered as an error and thus can be corrected. These repeated corrections to the inertial sensor’s velocity measurements can, therefore, be used to control the error growth and minimize the position drift. Nonetheless, it is still inadequate, mainly due to the remaining errors on the inertial sensor’s heading when the velocity corrections are used alone. Apart from the initialization issue, therefore, the heading drift problem still remains in such low-cost systems. In this research, two novel methods are developed and investigated to mitigate the heading drift problem when used with the velocity updates. The first method is termed Cardinal Heading Aided Inertial Navigation (CHAIN), where an algorithm is developed to use building ‘heading’ to aid the heading measurement in the Kalman Filter. The second method is termed the Rotated IMU (RIMU), where the foot-mounted inertial sensor is rotated about a single axis to increase the observability of the sensor’s heading. For the CHAIN, the method proposed has been investigated with real field trials using the low-cost Microstrain 3DM-GX3-25 inertial sensor. It shows a clear improvement in mitigating the heading drift error. It offers significant improvement in navigation accuracy for a long period, allowing autonomous pedestrian navigation for as long as 40 minutes with below 5 meters position error between start and end position. It does not require any extra heading sensors, such as a magnetometer or visual sensors such as a camera nor an extensive position or map database, and thus offers a cost-effective solution. Furthermore, its simplicity makes it feasible for it to be implemented in real-time, as very little computing capability is needed. For the RIMU, the method was tested with Nottingham Geospatial Institute (NGI) inertial data simulation software. Field trials were also undertaken using the same low-cost inertial sensor, mounted on a rotated platform prototype. This method improves the observability of the inertial sensor’s errors, resulting also in a decrease in the heading drift error at the expense of requiring extra components

Three-Phase Virtual Instrument Measurement System

Electrical engineering laboratory often involves measurement of current and voltage signals. Conventionally, it is accomplished by using various types of hardwired measurement equipments. If further signals information is required the oscilloscope becomes the preference. However, for measurement of voltage that is connected to the mains, prior knowledge to isolation is a must. Conventional oscilloscopes neither have the isolation function nor the data logging capabilities for further analysis. This paper presents the hardware and software development of a custom-built three-phase measurement system, equipped with isolation and data logging features. It also includes a description of the application of virtual instrumentation, written in LabVIEW that uses the developed hardware. A case study will also be presented

Mind-mapping strategy in process writing approach: Idea extension evidence for introductory paragraph

Extending ideas in essay writing is challenging for many ESL students, let alone the low ones. The students need help writing ideas, even in the introductory paragraph. Mind mapping strategy could help students develop ideas by forming wh-questions using identified keywords. Hence, this research is conducted to determine the evidence of a mind-mapping strategy in extending ideas for writing introductory paragraphs in the Malaysian University English Test (MUET) Writing Task 2 (Extended Essay). Also, it intends to explore the students’ steps in the mind-mapping strategy to extend ideas in the introductory paragraph writing process. The research design is a sequential explanatory mixed-method approach where data were gathered through a needs assessment survey, diagnostic tests, and semi-structured interviews. Process writing activities were designed as a treatment after the survey, and pre-test scores supported the necessity to employ the mind-mapping strategy to the experimental group. Conversely, a control group was formed to contrast the strategy with free writing activities. Test scores of the two groups after eight weeks of the treatment were compared using Klimova’s (2014) writing components. The diagnostic pre and post-test scores on ideas extension showed evidence of the strategy. The qualitative findings also augmented the strategy’s usefulness in five aspects: 1) as an idea generation strategy; 2) using keywords and wh-questions; 3) clear step-by-step processes; 4) improved idea development; and 5) the importance of a good beginning. Further study could expand the strategy’s advantages in idea extension and content paragraph organisation for the MUET writing tasks and other essay writing processes

Direct Torque Control of BLDC Motor with Constant Switching Frequency

Direct torque control (DTC) has become a popular technique for brushless motor control because it provides fast dynamic torque response. Hysteresis band control is the most popular techniques used in the DTC BLDC motor drive caused the simplest technique. However the conventional DTC have problems as switching frequency that varies with operating conditions and high torque ripple. This paper presents direct torque control (DTC) of BLDC motor with constant switching frequency torque controller. The torque ripple will get reduced by this method constant switching frequency operation. The feasibility of this method in minimizing the torque ripple is verified through some simulation results

Keperluan penggunaan modul etika kerja guru dalam meningkatkan penghayatan nilai pelajar

Untuk melahirkan masyarakat yang bertatasusila, bersatu padu, demokratik, adil dan progresif, setiap guru harus memainkan peranan sebagai role model kepada pelajar. Kepatuhan guru terhadap etika kerja Kementerian Pelajaran Malaysia (KPM), kod etika guru dan Standard Guru Malaysia perlu dititikberatkan bagi melahirkan golongan pendidikan yang memiliki nilai etika yang baik dan berkualiti tinggi. Menyedari kepentingan ini, satu modul etika kerja guru telah dibina khusus bagi meningkatkan pengetahuan, kefahaman dan amalan tentang etika kerja bertujuan melahirkan guru yang berkualiti pada masa kini dan pada masa hadapan. Artikel ini memberi tumpuan kepada pembinaan modul tersebut yang telah dibuat berdasarkan Model Pembinaan Modul yang telah perkenalkan oleh Sidek Noah. Dalam membangunkan sesebuah modul, Model ini telah menetapkan dua peringkat, iaitu sembilan langkah di peringkat pertama dan dua langkah di peringkat kedua. Modul etika kerja ini telah melalui kesemua peringkat yang dicadangkan. Berdasarkan hasil penilaian yang dilakukan oleh pakar penilai modul mendapati bahawa aras pekali secara keseluruhan bagi kesahan modul adalah 0.79 dan kebolehpercayaan Alpha Cronbach untuk modul etika kerja KPM adalah tinggi iaitu 0.95. Dapatan kajian membuktikan bahawa modul etika kerja KPM ini mempunyai kesahan dan kebolehpercayaan yang tinggi. Kajian ini mendapati, semua aktiviti yang terkandung dalam modul ini adalah sesuai dan boleh digunakan sebagai alat, bahan, sumber dan panduan yang boleh memberi bimbingan, kesedaran, keinsafan, semangat dan motivasi kepada semua guru sekolah di seluruh Malaysia. Ia juga berupaya meningkatkan kesedaran dan kualiti tingkah laku para guru dan pelajar sekaligus meningkatkan penghayatan nilai murni dalam kalangan guru dan pelajar. Modul yang dihasilkan ini juga penting sebagai bahan rujukan untuk melahirkan para guru yang berkualiti pada masa akan datang

Teachers’ techniques in developing of akhlaq and values in the students

Akhlaq and moral values among students who want to be born by the national education system can be achieved through the implementation of the inculcation of noble values in the teachings. Therefore, this article presents the findings related to the the students’ perception of the techniques of the inculcation of noble values during classroom instructions.This descriptive survey study approach was conducted in one of the schools in the district of Kuala Muda/Yan in Kedah.A total number of Forms 4 and 2 students were selected as the respondents to complete the questionnaire.The study findings found that based on students’ perception, there were five techniques that gained overall moderately high mean value, namely modelling, lecture, discussion, positive reinforcement and negative reinforcement. Meanwhile, other techniques were at medium low level. In summary, this study has shown that certain application techniques in instilling values should be practiced by teachers towards to increase students’ moral understanding and development towards realizing the National Education Philosophy and the Malaysian Education Blueprint 2013-2025 in the context of producing human capital that are stable and harmon

Questioning strategy in process writing approach : Evidence for idea extension in introductory paragraph

Many students at the tertiary level find it hard to have ideas in the introductory paragraph. One way to overcome that issue is by applying a questioning strategy. The convergent parallel design of qualitative and quantitative methods is adopted to collect data through a need assessment survey, diagnostic tests, and face-to-face interviews. Process writing activities were designed after the needs assessment survey findings, and pre-test scores showed the necessity to introduce the questioning strategy to the experimental group. On the other hand, the control group was formed to contrast the strategy with free writing activities. Tests scores of the two groups after 18 weeks of the writing process activities were compared using Klimova’s (2014) writing assessment criteria. The scores of diagnostic pre and post-tests on ideas extension showed that most of the experimental students’ scores were better than those in the control group. The questioning strategy in the process writing approach improved the students’ ideas for the introductory paragraph compared to free process writing. The strategy’s effectiveness could be extended to help students develop ideas and organise content paragraphs